KS3 Science. Heat and Energy

Transcription

1 KS3 Science Heat and Energy

2 Heat and Energy Key Words Write a definition for each of the key words listed below Key words States of matter Melt Freeze Evaporate Condense Heat Conduction Convention Radiation Forms of Energy 2

3 1. Kinetic Theory States of Matter Answer the following true or false questions put a T or F in the space at the end of each question. The three states of matter are solid, gas and lava. Liquids can flow. Solids take the shape of their container. Air is not made of particles. It is easy to squash a liquid. A gas is highly compressible. People have all three states of matter in their bodies. In a solid, the particles are further apart than in a liquid. Complete the diagrams below to show the arrangement of particles in a solid, liquid and gas: Solid Liquid Gas Complete the diagrams below to show the arrangement of particles in a solid, liquid and gas: Fill in the missing words about particles. Words may be used more than once or not at all. In a., the particles are held very. together in a. pattern. They can. about a fixed point. The particles don t. from their position, so all solids keep a. shape and. and can t. like liquids. Particles in a. are still close together but are arranged. (not in a pattern). They can move by. over each other. They do not have a fixed. and take the shape of their container. In a. the. are far apart. They can move. in any direction. Gases can be. easily as there is lots of free space between the particles. SLIDING SOLID CLOSELY VIBRATE GAS COMPRESSED MOVE FIXED LIQUID RANDOMLY VOLUME SHAPE PARTICLES RANDOMLY REGULAR 3

4 1. Kinetic Theory Changes of State Complete the diagram below to show a solid liquid and gas. Label the arrow with a word to describe how the materials can change state. Identify the following as evaporation, condensation, melting or freezing: A cold can of cola from the fridge has tiny drops of water on it When you burn a candle the wax runs down the side When you boil water it turns into water vapour On a cold day you can see your breath When you hang washing outside, it dries If you leave ice cream out on a hot day When it warms up snow becomes slushy When you have made a pot out of clay, it dries out When you have a shower, the mirror steams up SLIDING SOLID CLOSELY VIBRATE GAS COMPRESSED MOVE FIXED LIQUID If you put water RANDOMLY in the freezer it VOLUME turns into a SHAPE solid PARTICLES RANDOMLY REGULAR 4

5 2. Conduction Fill in the gaps using the words below: Conduc on Heated Thermal energy Par cles Vibrate When a substance is, its gain energy and vibrate more vigorously. The particles bump into nearby particles and make them more. This passes the through the substance by, from the hot end to the cold end. Look at each of the scenarios below. For each, state which paper clip will fall off last and explain why.. 5

6 3. Convection Use the pictures below to describe how heat energy is transferred by convection Stage 1 Stage 2 Stage 3 Stage 4 Heat travels by in fluids because the particles in a can move around and spread Stage 1: A purple crystal is dropped into the water. When we the beaker under the purple crystals they start to Heat energy conducted through the starts to heat the water. Stage 2: The water particles being heated are given more and begin to move The part of the water begins to Stage 3: When the water reaches the top of the beaker it is pushed sideways by more hot water moving Stage 4: The warm water transfers some energy to the water around it. As it does this it begins to down and This cooler water can move to take the place of the rising water. This water is again heated and begins to This movement of water around the beaker is called a which eventually spreads (and purple dye) through all the water in the beaker. Keywords Liquid Convection Rise Hotter Energy Faster Heat energy Sinks Cooler Heat Upwards Hot Glass Cool Convection current Dissolve 6

7 4. Radiation Fill in the gaps using the words below: Sun Radiation white Particles Transfer absorb There are three methods of heat. conduction, convection and radiation. Radiation is the only method which does not require. Because it does not require particles.can travel through a vacuum; this is how heat reaches us from the. All hot objects emit radiation. Objects that are dark colours.. the energy. Objects which are. reflect the radiation. Decide if the following statements are true or false All hot objects emit radiation White colours absorb the most radiation The hotter an object is the more radiation it will absorb Radiation can travel through space A good insulator can stop radiation Radiation cannot travel through glass Match the statements People paint houses in hot countries white Paint solar panels for making electricity black... People are wrapped in shiny foil after a marathon... Thermos flasks are shiny on the inside... To absorb as much radiation from the sun as possible To reflect the heat back into the drink and keep it warm To reflect their own heat back into them To reflect the heat of the sun away and keep them cool 7

8 5. Forms of energy The following words are all mixed up names for different types of energy. Unscramble t the letters to find the types of energy a-h A) glith B) Tacslie C) Duons D) Tenpliato E) Hamlert F) Cleerlicat Choose a type of energy which fits the descriptions A) to H) below. A) The type of energy that moving objects have.. B) A very useful type of energy that flows along wires C) A type of energy stored due to gravity and height above ground D) Luminous objects give off this energy E) The potential energy stored in a stretched rubber band F) Energy that can be released b y a type of reaction G) Energy that noisy objects transmit H) Energy that everything above a temperature of absolute zero possesses Draw simple energy transfer diagrams for the objects below. Indicate which energy is useful and which is wasted 1. TV 2. Speaker 3. Fire 4. Falling Piano 5. Burning candle 8

9 6. Sankey Diagrams A Sankey diagram shows you how well a machine uses energy. In other words, it tells you if it uses it efficiently (without much waste) or inefficiently (with a lot of waste). The thickness of the arrows shows how much energy is involved. (The length of the arrows does not matter in a Sankey Diagram.) Useful energy transfers are shown going left to right. Wasteful energy transfers are shown going upwards. 1. Write in these labels on the diagram above: INPUT ENERGY USEFUL OUTPUT ENERGY WASTED OUTPUT ENERGY 2. A normal filament bulb transfers 10% of energy as light (useful) but 90% as heat energy (wasted). Draw a Sankey diagram in the space below. Remember to label it with: INPUT ENERGY, USEFUL OUTPUT ENERGY, WASTED OUTPUT ENERGY 9

10 6. Sankey Diagrams 3. An energy efficient bulb transfers 40% of the energy as useful light energy. How much energy is transferred as heat? Draw a Sankey Diagram in the space below Remember to label it with: INPUT ENERGY, USEFUL OUTPUT ENERGY, WASTED OUTPUT ENERGY 4. A team of scientists test an old banger car. They find out that only 10% of the energy is transferred as kinetic energy (useful) and 70% is transferred as heat energy (wasted). How much energy is wasted as sound? Draw a Sankey Diagram in the space below Remember to label it with: INPUT ENERGY, USEFUL OUTPUT ENERGY, WASTED OUTPUT ENERGY 10

11 7. Power Answer the questions below: 1. What is meant by the power rating of an electricity appliance? 2. How can the power of an appliance be calculated? 3. What are the units of power? 4. What is the power of an electric fire that transfers 10,000J of energy in 5 seconds? 5. What is the power rating of a light bulb that transfers 120 joules of energy in 2 seconds? 6. Billy runs up the stairs in 5 seconds. If he transfers 1,000,000J of energy in this time what is his power rating? 7. How much energy does a 150W light bulb transfer in a) one second, b) one minute? 11

12 Summary Questions Answer the summary questions 1. Complete the sentences A B C D The instrument used to measure temperature is The unit used to measure temperature is The boiling point of water is The melting point of water is 2. Complete the sentences: Slower Gases Together Apart Contracts Cool Expands Faster When a metal rod is heated, it This is because the particles vibrate and s move each other further When the metal rod is allowed to, it The particles vibrate..and so they move Liquids and expand and contract in the same way 3. A steel saucepan has a wooden handle A Why would it not be sensible to use a metal handle? B What property of wood makes it a good choice for the handle? C Suggest another material that could be used to make the handle. 4. Add arrows to the diagram below to show the convection currents in air that you would expect around a bonfire. 12

13 Summary Questions Answer the summary question 5. Match the beginning of each sentence with the correct ending. Beginnings A An electric drill transfers electrical energy B A diver diving off a diving board transfers gravitational energy C An electric fire transfers electrical energy D A filament lamp transfers electrical energy E A radio transfers electrical energy Endings 1 into sound energy. 2 into light energy and heat energy. 3 into movement energy and sound energy. 4 mainly into heat energy. 5 into kinetic energy. 6. Scientists say that energy is conserved. In a television, electrical energy is transferred into light, heat and sound. A Draw an energy transfer diagram to represent these energy transfers. B Explain how energy is conserved when a TV is working.. C Which part of the energy transfer is not really useful?. D Use this idea to explain why a television is not a 100% efficient object. `. 13